2,4,8,10-Tetraoxaspiro[5,5]undecanes having a hydroxyl or ester group directly or via an alkylene or phenylene group at the 3- or 9-position, are useful as starting materials for polymers with good workability, heat resistance, water resistance, mechanical strength, adhesion, anti-cracking properties, or the like, or useful as crosslinking agents for exhibiting these performances (or as starting materials for such crosslinking agents) (for example, see U.S. Pat. No. 2,945,008, JP-A-60-195168 (“JP-A” means unexamined published Japanese patent application), JP-A-61-47722, JP-A-61-195136, JP-A-2-187424, JP-A-4-88078, JP-A-2001-277421; Polymer (Korea), Vol. 4, No. 5, p. 448-455 (1990); and Polymer Int., Vol. 52, p. 1633-1640 (2003)).
In general, 2,4,8,10-tetraoxaspiro[5,5]undecanes can be synthesized by dehydration condensation of a carbonyl compound and pentaerythritol (C(CH2OH)4) in the presence of an acid catalyst (for example, see SYNTHETIC COMMUNICATIONS, Vol. 29, No. 9, p. 1601-1606 (1999); and Bull. Chem. Soc. Jpn., Vol. 75, p. 2195-2205 (2002)). A certain carbonyl compound having a hydroxyl or ester group in its molecule may be used as a starting material, to synthesize 2,4,8,10-tetraoxaspiro[5,5]undecanes that have a hydroxyl or ester group directly or via an alkylene or phenylene group at the 3- or 9-position and that are useful as starting materials for polymers or as crosslinking agents (or as starting materials for such crosslinking agents) (for example, see U.S. Pat. No. 3,092,640; Tetrahedron, 60, p. 4789-4800 (2004); and J. Org. Chem., Vol. 24, p. 1958-1961 (1959)).
In these cases, however, side reactions, such as self-condensation and transesterification, can occur at the same time. As shown in SYNTHETIC COMMUNICATIONS, Vol. 29, No. 9, p. 1601-1606 (1999), and Bull. Chem. Soc. Jpn., Vol. 75, p. 2195-2205 (2002), the target spirocyclic acetal-forming reaction is slow particularly in the case of ketones, as compared with the case of aldehydes, and thus it is not few that the target substance of high purity cannot be efficiently produced from the ketones.
For the purpose of solving this problem, there is a known synthesis in which a diketal (3,3,9,9-tetramethyl-2,4,8,10-tetraoxaspiro[5,5]undecane) is transiently prepared from acetone and pentaerythritol (C(CH2OH)4), and 3,9-dialkyl (or diaryl)-3,9-bis(methoxycarbonylalkyl)-2,4,8,10-tetraoxaspiro[5,5]undecane is synthesized in high yield and high purity by acetal exchange reaction of the diketal and a ketoester in methanol with an acid catalyst (J. Org. Chem., Vol. 26, p. 2515-2518 (1961)).
However, this method has a complicated process and a large number of steps, and thus is not economically preferred. Also in this method, the problem of side reactions, such as transesterification, is not substantially resolved. Thus, this method is not applicable in the synthesis of 3,9-dialkyl (or diaryl)-3,9-bis[acyloxymethyl (or hydroxymethyl)]-2,4,8,10-tetraoxaspiro[5,5]undecane.
As described above, hitherto, there is no known method of efficiently synthesizing 3,9-dialkyl (or dicycloalkyl or diaryl)-3,9-bis[acyloxymethyl (or hydroxymethyl)]-2,4,8,10-tetraoxaspiro[5,5]undecane. Thus, hitherto, 3,9-dimethyl-3,9-bis(hydroxymethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane or a diacyl derivative thereof, and polyesters which are produced with a starting material of such a diol as 3,9-dimethyl-3,9-bis(hydroxymethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, are unknown.